This is a small miniball with an alternative circuit. Since I didn't have the parts to build a true type 2 solarengine, I made a long time
oscillator with the on time controlled by a photodiode. This should give the ball some phototropic behaviour. The gearbox is of the
same type as those in my turbot, but with one less gear. The power is quite sufficient anyway, with the ball making a small "burn-out"
everytime it fires. The photodiode is looking backwards, so the ball is photophobic in the true sense, when it ends up the shadows, it almost
empties it's cap in a "panic" motion.

The finished bot, and the mechanism outside of the plastic sphere

The components...

Here is an early design plan for the microball:

And here are the schematics (NOTE: It is probably a good idea to ground all unused inputs!)